ZnO对正十八烷@PMMA微胶囊结晶性能的影响

Effect of ZnO on the crystallization properties of n-octadecane@PMMA microcapsules

为了抑制相变材料微胶囊(MicroPCMs)的过冷结晶,采用水热合成法,在140℃条件下,以ZnCl2为前驱体,硬脂酸(SA)为表面修饰剂,相变材料正十八烷(n-Oct)为反应介质,制备了包含ZnO纳米颗粒的n-Oct悬浮液。以此悬浮液作为相变材料,采用悬浮自由基聚合制备交联聚甲基丙烯酸甲酯(PMMA)为壁材的MicroPCMs(ZnO/n-Oct@PMMA)。扫描电镜(SEM)和透射电镜(TEM)测试表明,微胶囊呈核壳结构,表面有凹陷,粒径为1~5μm,囊内ZnO颗粒大约10~100nm。差示扫描量热分析(DSC)和热重分析(TG)测试表明,ZnO的存在对胶囊的耐热性能影响不大,但使微胶囊的异相成核结晶焓增加了47.8%,较好地抑制了相变材料微胶囊的过冷结晶行为。

In order to inhibit the supercooling crystallization of microcapsule phase change materials(MicroPCMs),an n-octadecane(n-Oct)suspension containing zinc oxide(ZnO)nanoparticles was prepared by hydrothermal synthesis method using zinc chloride(ZnCl2)as the precursor,stearic acid(SA)as the surface modifier,and phase change material(n-Oct)as the reaction medium at the temperature of 140℃.The suspension was used as a phase change material to prepare MicroPCMs(ZnO/n-oct@PMMA)with a crosslinked polymethyl methacrylate(PMMA)as the wall by a suspension free radical polymerization.The scanning electron microscopy(SEM)and transmission electron microscopy(TEM)tests showed that the microcapsules had a core-shell structure,and the surface had depressions,with the particle size of 1~5μm,and the ZnO particles in the microcapsules were about 10~100nm.The differential scanning calorimetry(DSC)and thermogravimetric analysis(TG)tests indicated that the presence of ZnO had little effect on the heat resistance of the microcapsules,but it increased the heterogeneous nucleation crystallization enthalpy of the microcapsules by 47.8%,which well inhibited the supercooling crystallization behavior of the MicroPCMs.